docs(rate-limiting): add file name

Author: Zerotask

content/security/rate-limiting.md

@@ -9,6 +9,7 @@ $ npm i --save @nestjs/throttler
 Once the installation is complete, the `ThrottlerModule` can be configured as any other Nest package with `forRoot` or `forRootAsync` methods.
 
 ```typescript
+@@filename(app.module.ts)
 @Module({
   imports: [
     ThrottlerModule.forRoot({